Electrochemistry
3.0 Electrochemical Cells
3.0 Electrochemical Cells
There are two types of electrochemical cells
$(i)$ Galvanic Cells (or Voltaic Cells)
$(ii)$ Electrolytic Cell
Galvanic Cells (or Voltaic Cells):
A galvanic cell or voltaic cell, named after Luigi Galvani or Alessandro Volta is an electrochemical cell which converts chemical energy into electrical energy from the spontaneous redox reactions occurring within the cell. In this electricity is produced by the oxidation or reduction reactions. The reaction responsible for the production of electricity is taking place in two separate sections or compartments. Each compartment consists of appropriate or suitable electrolytic solution and a metallic conductor. The compartments containing the electrolytic solution and metallic conductor are termed as half cells. Here metallic conductor acts as a electrode.In this system, compartments are connected through salt bridge( discussed later) and electrodes are joined by wire through galvanometer and the electricity begins to flow. Spontaneous reactions are labelled by galvanic cells. Chemical energy is converted into electrical energy.
Electrolytic Cell:
Non spontaneous reactions which require electrical energy are called electrolytic cells. Here electric current removes electrons from one reactant and gives electrons to other. For example: Consider the electrolysis process, used to decompose stable compounds like ${H_2}O$ into its elements and electroplating.
An electrolytic cell is an arrangement where there is a conduction of electricity through a solution or molten salt by the movement of ions.
Non Spontaneous reactions are labelled by electrolytic cells. Electrical energy is converted into chemical energy.
Electrolytic conduction can be best illustrated or explained by the reference to an electrolytic cell
Two rods or plates are required which are connected with the terminals of the battery for the passage of electric current through electrolytic conduction. These rods or plates are termed as electrodes. There are two electrodes i.e anode and cathode.
Anode is the electrode through which electric current enters the electrolytic solution (or electrolyte). It is positive electrode.
Cathode is the electrode through which electric current leaves the electrolytic solution (or electrolyte). It is negative electrode.
This entire set up except the external battery is called cell .From the negative end of the external battery, the electrons are received by the negative electrode of the cell. And the electrons which are received at the negative electrode are given back to the positive terminal of the external battery from the positive electrode of the cell where electrons are released as a result of oxidation reaction. Due to this, ions movement occurs and hence the electrolytic conduction.
